-/* SPDX-License-Identifier: GPL-2.0 */
/******************************************************************************
* ring.h
*
* Shared producer-consumer ring macros.
*
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
* Tim Deegan and Andrew Warfield November 2004.
*/
#ifndef __XEN_PUBLIC_IO_RING_H__
#define __XEN_PUBLIC_IO_RING_H__
+/*
+ * When #include'ing this header, you need to provide the following
+ * declaration upfront:
+ * - standard integers types (uint8_t, uint16_t, etc)
+ * They are provided by stdint.h of the standard headers.
+ *
+ * In addition, if you intend to use the FLEX macros, you also need to
+ * provide the following, before invoking the FLEX macros:
+ * - size_t
+ * - memcpy
+ * - grant_ref_t
+ * These declarations are provided by string.h of the standard headers,
+ * and grant_table.h from the Xen public headers.
+ */
+
#include <xen/interface/grant_table.h>
typedef unsigned int RING_IDX;
/* Round a 32-bit unsigned constant down to the nearest power of two. */
-#define __RD2(_x) (((_x) & 0x00000002) ? 0x2 : ((_x) & 0x1))
+#define __RD2(_x) (((_x) & 0x00000002) ? 0x2 : ((_x) & 0x1))
#define __RD4(_x) (((_x) & 0x0000000c) ? __RD2((_x)>>2)<<2 : __RD2(_x))
#define __RD8(_x) (((_x) & 0x000000f0) ? __RD4((_x)>>4)<<4 : __RD4(_x))
#define __RD16(_x) (((_x) & 0x0000ff00) ? __RD8((_x)>>8)<<8 : __RD8(_x))
* A ring contains as many entries as will fit, rounded down to the nearest
* power of two (so we can mask with (size-1) to loop around).
*/
-#define __CONST_RING_SIZE(_s, _sz) \
- (__RD32(((_sz) - offsetof(struct _s##_sring, ring)) / \
- sizeof(((struct _s##_sring *)0)->ring[0])))
-
+#define __CONST_RING_SIZE(_s, _sz) \
+ (__RD32(((_sz) - offsetof(struct _s##_sring, ring)) / \
+ sizeof(((struct _s##_sring *)0)->ring[0])))
/*
* The same for passing in an actual pointer instead of a name tag.
*/
-#define __RING_SIZE(_s, _sz) \
- (__RD32(((_sz) - (long)&(_s)->ring + (long)(_s)) / sizeof((_s)->ring[0])))
+#define __RING_SIZE(_s, _sz) \
+ (__RD32(((_sz) - (long)(_s)->ring + (long)(_s)) / sizeof((_s)->ring[0])))
/*
* Macros to make the correct C datatypes for a new kind of ring.
*
* To make a new ring datatype, you need to have two message structures,
- * let's say struct request, and struct response already defined.
+ * let's say request_t, and response_t already defined.
*
* In a header where you want the ring datatype declared, you then do:
*
- * DEFINE_RING_TYPES(mytag, struct request, struct response);
+ * DEFINE_RING_TYPES(mytag, request_t, response_t);
*
* These expand out to give you a set of types, as you can see below.
* The most important of these are:
*
- * struct mytag_sring - The shared ring.
- * struct mytag_front_ring - The 'front' half of the ring.
- * struct mytag_back_ring - The 'back' half of the ring.
+ * mytag_sring_t - The shared ring.
+ * mytag_front_ring_t - The 'front' half of the ring.
+ * mytag_back_ring_t - The 'back' half of the ring.
*
* To initialize a ring in your code you need to know the location and size
* of the shared memory area (PAGE_SIZE, for instance). To initialise
* the front half:
*
- * struct mytag_front_ring front_ring;
- * SHARED_RING_INIT((struct mytag_sring *)shared_page);
- * FRONT_RING_INIT(&front_ring, (struct mytag_sring *)shared_page,
- * PAGE_SIZE);
+ * mytag_front_ring_t front_ring;
+ * SHARED_RING_INIT((mytag_sring_t *)shared_page);
+ * FRONT_RING_INIT(&front_ring, (mytag_sring_t *)shared_page, PAGE_SIZE);
*
* Initializing the back follows similarly (note that only the front
* initializes the shared ring):
*
- * struct mytag_back_ring back_ring;
- * BACK_RING_INIT(&back_ring, (struct mytag_sring *)shared_page,
- * PAGE_SIZE);
+ * mytag_back_ring_t back_ring;
+ * BACK_RING_INIT(&back_ring, (mytag_sring_t *)shared_page, PAGE_SIZE);
*/
-#define DEFINE_RING_TYPES(__name, __req_t, __rsp_t) \
- \
-/* Shared ring entry */ \
-union __name##_sring_entry { \
- __req_t req; \
- __rsp_t rsp; \
-}; \
- \
-/* Shared ring page */ \
-struct __name##_sring { \
- RING_IDX req_prod, req_event; \
- RING_IDX rsp_prod, rsp_event; \
- uint8_t pad[48]; \
- union __name##_sring_entry ring[1]; /* variable-length */ \
-}; \
- \
-/* "Front" end's private variables */ \
-struct __name##_front_ring { \
- RING_IDX req_prod_pvt; \
- RING_IDX rsp_cons; \
- unsigned int nr_ents; \
- struct __name##_sring *sring; \
-}; \
- \
-/* "Back" end's private variables */ \
-struct __name##_back_ring { \
- RING_IDX rsp_prod_pvt; \
- RING_IDX req_cons; \
- unsigned int nr_ents; \
- struct __name##_sring *sring; \
-};
-
+#define DEFINE_RING_TYPES(__name, __req_t, __rsp_t) \
+ \
+/* Shared ring entry */ \
+union __name##_sring_entry { \
+ __req_t req; \
+ __rsp_t rsp; \
+}; \
+ \
+/* Shared ring page */ \
+struct __name##_sring { \
+ RING_IDX req_prod, req_event; \
+ RING_IDX rsp_prod, rsp_event; \
+ uint8_t __pad[48]; \
+ union __name##_sring_entry ring[1]; /* variable-length */ \
+}; \
+ \
+/* "Front" end's private variables */ \
+struct __name##_front_ring { \
+ RING_IDX req_prod_pvt; \
+ RING_IDX rsp_cons; \
+ unsigned int nr_ents; \
+ struct __name##_sring *sring; \
+}; \
+ \
+/* "Back" end's private variables */ \
+struct __name##_back_ring { \
+ RING_IDX rsp_prod_pvt; \
+ RING_IDX req_cons; \
+ unsigned int nr_ents; \
+ struct __name##_sring *sring; \
+}; \
+ \
/*
* Macros for manipulating rings.
*
*/
/* Initialising empty rings */
-#define SHARED_RING_INIT(_s) do { \
- (_s)->req_prod = (_s)->rsp_prod = 0; \
- (_s)->req_event = (_s)->rsp_event = 1; \
- memset((_s)->pad, 0, sizeof((_s)->pad)); \
+#define SHARED_RING_INIT(_s) do { \
+ (_s)->req_prod = (_s)->rsp_prod = 0; \
+ (_s)->req_event = (_s)->rsp_event = 1; \
+ (void)memset((_s)->__pad, 0, sizeof((_s)->__pad)); \
} while(0)
-#define FRONT_RING_ATTACH(_r, _s, _i, __size) do { \
- (_r)->req_prod_pvt = (_i); \
- (_r)->rsp_cons = (_i); \
- (_r)->nr_ents = __RING_SIZE(_s, __size); \
- (_r)->sring = (_s); \
+#define FRONT_RING_ATTACH(_r, _s, _i, __size) do { \
+ (_r)->req_prod_pvt = (_i); \
+ (_r)->rsp_cons = (_i); \
+ (_r)->nr_ents = __RING_SIZE(_s, __size); \
+ (_r)->sring = (_s); \
} while (0)
#define FRONT_RING_INIT(_r, _s, __size) FRONT_RING_ATTACH(_r, _s, 0, __size)
-#define BACK_RING_ATTACH(_r, _s, _i, __size) do { \
- (_r)->rsp_prod_pvt = (_i); \
- (_r)->req_cons = (_i); \
- (_r)->nr_ents = __RING_SIZE(_s, __size); \
- (_r)->sring = (_s); \
+#define BACK_RING_ATTACH(_r, _s, _i, __size) do { \
+ (_r)->rsp_prod_pvt = (_i); \
+ (_r)->req_cons = (_i); \
+ (_r)->nr_ents = __RING_SIZE(_s, __size); \
+ (_r)->sring = (_s); \
} while (0)
#define BACK_RING_INIT(_r, _s, __size) BACK_RING_ATTACH(_r, _s, 0, __size)
/* How big is this ring? */
-#define RING_SIZE(_r) \
+#define RING_SIZE(_r) \
((_r)->nr_ents)
/* Number of free requests (for use on front side only). */
-#define RING_FREE_REQUESTS(_r) \
+#define RING_FREE_REQUESTS(_r) \
(RING_SIZE(_r) - ((_r)->req_prod_pvt - (_r)->rsp_cons))
/* Test if there is an empty slot available on the front ring.
* (This is only meaningful from the front. )
*/
-#define RING_FULL(_r) \
+#define RING_FULL(_r) \
(RING_FREE_REQUESTS(_r) == 0)
/* Test if there are outstanding messages to be processed on a ring. */
-#define RING_HAS_UNCONSUMED_RESPONSES(_r) \
+#define RING_HAS_UNCONSUMED_RESPONSES(_r) \
((_r)->sring->rsp_prod - (_r)->rsp_cons)
-#define RING_HAS_UNCONSUMED_REQUESTS(_r) \
- ({ \
- unsigned int req = (_r)->sring->req_prod - (_r)->req_cons; \
- unsigned int rsp = RING_SIZE(_r) - \
- ((_r)->req_cons - (_r)->rsp_prod_pvt); \
- req < rsp ? req : rsp; \
- })
+#define RING_HAS_UNCONSUMED_REQUESTS(_r) ({ \
+ unsigned int req = (_r)->sring->req_prod - (_r)->req_cons; \
+ unsigned int rsp = RING_SIZE(_r) - \
+ ((_r)->req_cons - (_r)->rsp_prod_pvt); \
+ req < rsp ? req : rsp; \
+})
/* Direct access to individual ring elements, by index. */
-#define RING_GET_REQUEST(_r, _idx) \
+#define RING_GET_REQUEST(_r, _idx) \
(&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].req))
+#define RING_GET_RESPONSE(_r, _idx) \
+ (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].rsp))
+
/*
- * Get a local copy of a request.
+ * Get a local copy of a request/response.
*
- * Use this in preference to RING_GET_REQUEST() so all processing is
+ * Use this in preference to RING_GET_{REQUEST,RESPONSE}() so all processing is
* done on a local copy that cannot be modified by the other end.
*
* Note that https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145 may cause this
- * to be ineffective where _req is a struct which consists of only bitfields.
+ * to be ineffective where dest is a struct which consists of only bitfields.
*/
-#define RING_COPY_REQUEST(_r, _idx, _req) do { \
- /* Use volatile to force the copy into _req. */ \
- *(_req) = *(volatile typeof(_req))RING_GET_REQUEST(_r, _idx); \
+#define RING_COPY_(type, r, idx, dest) do { \
+ /* Use volatile to force the copy into dest. */ \
+ *(dest) = *(volatile typeof(dest))RING_GET_##type(r, idx); \
} while (0)
-#define RING_GET_RESPONSE(_r, _idx) \
- (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].rsp))
+#define RING_COPY_REQUEST(r, idx, req) RING_COPY_(REQUEST, r, idx, req)
+#define RING_COPY_RESPONSE(r, idx, rsp) RING_COPY_(RESPONSE, r, idx, rsp)
/* Loop termination condition: Would the specified index overflow the ring? */
-#define RING_REQUEST_CONS_OVERFLOW(_r, _cons) \
+#define RING_REQUEST_CONS_OVERFLOW(_r, _cons) \
(((_cons) - (_r)->rsp_prod_pvt) >= RING_SIZE(_r))
/* Ill-behaved frontend determination: Can there be this many requests? */
-#define RING_REQUEST_PROD_OVERFLOW(_r, _prod) \
+#define RING_REQUEST_PROD_OVERFLOW(_r, _prod) \
(((_prod) - (_r)->rsp_prod_pvt) > RING_SIZE(_r))
+/* Ill-behaved backend determination: Can there be this many responses? */
+#define RING_RESPONSE_PROD_OVERFLOW(_r, _prod) \
+ (((_prod) - (_r)->rsp_cons) > RING_SIZE(_r))
-#define RING_PUSH_REQUESTS(_r) do { \
- virt_wmb(); /* back sees requests /before/ updated producer index */ \
- (_r)->sring->req_prod = (_r)->req_prod_pvt; \
+#define RING_PUSH_REQUESTS(_r) do { \
+ virt_wmb(); /* back sees requests /before/ updated producer index */\
+ (_r)->sring->req_prod = (_r)->req_prod_pvt; \
} while (0)
-#define RING_PUSH_RESPONSES(_r) do { \
- virt_wmb(); /* front sees responses /before/ updated producer index */ \
- (_r)->sring->rsp_prod = (_r)->rsp_prod_pvt; \
+#define RING_PUSH_RESPONSES(_r) do { \
+ virt_wmb(); /* front sees resps /before/ updated producer index */ \
+ (_r)->sring->rsp_prod = (_r)->rsp_prod_pvt; \
} while (0)
/*
* field appropriately.
*/
-#define RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(_r, _notify) do { \
- RING_IDX __old = (_r)->sring->req_prod; \
- RING_IDX __new = (_r)->req_prod_pvt; \
- virt_wmb(); /* back sees requests /before/ updated producer index */ \
- (_r)->sring->req_prod = __new; \
- virt_mb(); /* back sees new requests /before/ we check req_event */ \
- (_notify) = ((RING_IDX)(__new - (_r)->sring->req_event) < \
- (RING_IDX)(__new - __old)); \
+#define RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(_r, _notify) do { \
+ RING_IDX __old = (_r)->sring->req_prod; \
+ RING_IDX __new = (_r)->req_prod_pvt; \
+ virt_wmb(); /* back sees requests /before/ updated producer index */\
+ (_r)->sring->req_prod = __new; \
+ virt_mb(); /* back sees new requests /before/ we check req_event */ \
+ (_notify) = ((RING_IDX)(__new - (_r)->sring->req_event) < \
+ (RING_IDX)(__new - __old)); \
} while (0)
-#define RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(_r, _notify) do { \
- RING_IDX __old = (_r)->sring->rsp_prod; \
- RING_IDX __new = (_r)->rsp_prod_pvt; \
- virt_wmb(); /* front sees responses /before/ updated producer index */ \
- (_r)->sring->rsp_prod = __new; \
- virt_mb(); /* front sees new responses /before/ we check rsp_event */ \
- (_notify) = ((RING_IDX)(__new - (_r)->sring->rsp_event) < \
- (RING_IDX)(__new - __old)); \
+#define RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(_r, _notify) do { \
+ RING_IDX __old = (_r)->sring->rsp_prod; \
+ RING_IDX __new = (_r)->rsp_prod_pvt; \
+ virt_wmb(); /* front sees resps /before/ updated producer index */ \
+ (_r)->sring->rsp_prod = __new; \
+ virt_mb(); /* front sees new resps /before/ we check rsp_event */ \
+ (_notify) = ((RING_IDX)(__new - (_r)->sring->rsp_event) < \
+ (RING_IDX)(__new - __old)); \
} while (0)
-#define RING_FINAL_CHECK_FOR_REQUESTS(_r, _work_to_do) do { \
- (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \
- if (_work_to_do) break; \
- (_r)->sring->req_event = (_r)->req_cons + 1; \
- virt_mb(); \
- (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \
+#define RING_FINAL_CHECK_FOR_REQUESTS(_r, _work_to_do) do { \
+ (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \
+ if (_work_to_do) break; \
+ (_r)->sring->req_event = (_r)->req_cons + 1; \
+ virt_mb(); \
+ (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r); \
} while (0)
-#define RING_FINAL_CHECK_FOR_RESPONSES(_r, _work_to_do) do { \
- (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \
- if (_work_to_do) break; \
- (_r)->sring->rsp_event = (_r)->rsp_cons + 1; \
- virt_mb(); \
- (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \
+#define RING_FINAL_CHECK_FOR_RESPONSES(_r, _work_to_do) do { \
+ (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \
+ if (_work_to_do) break; \
+ (_r)->sring->rsp_event = (_r)->rsp_cons + 1; \
+ virt_mb(); \
+ (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \
} while (0)
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